package com.pingan.license.utils;

/**
 * @AUTHOR:LIUCHAO;
 * @DATE: 2020/12/1 8:59
 */



import java.security.*;
import javax.crypto.*;

    /**
     * DES加解密算法
     */
    public class DES {
        private static String strDefaultKey = "加密的公钥";
        private Cipher encryptCipher = null;
        private Cipher decryptCipher = null;


        /**
         * 默认构造方法，使用默认密钥
         * @throws Exception
         */
        public DES() throws Exception {
            this(strDefaultKey);
        }


        /**
         * 指定密钥构造方法
         * @param strKey 指定的密钥
         * @throws Exception
         */
        public DES(String strKey) throws Exception {
            Security.addProvider(new com.sun.crypto.provider.SunJCE());
            Key key = getKey(strKey.getBytes());
            encryptCipher = Cipher.getInstance("DES");
            encryptCipher.init(Cipher.ENCRYPT_MODE, key);
            decryptCipher = Cipher.getInstance("DES");
            decryptCipher.init(Cipher.DECRYPT_MODE, key);
        }


        /**
         * 加密字符串
         * @param strIn 需加密的字符串
         * @return 加密后的字符串
         * @throws Exception
         */
        public String encrypt(String strIn) throws Exception {
            return byteArr2HexStr(encrypt(strIn.getBytes()));
        }


        /**
         * 加密字节数组
         * @param arrB 需加密的字节数组
         * @return 加密后的字节数组
         * @throws Exception
         */
        public byte[] encrypt(byte[] arrB) throws Exception {
            return encryptCipher.doFinal(arrB);
        }



        /**
         * 解密字符串
         * @param strIn 需解密的字符串
         * @return 解密后的字符串
         * @throws Exception
         */
        public String decrypt(String strIn) throws Exception {
            return new String(decrypt(hexStr2ByteArr(strIn)));
        }


        /**
         * 解密字节数组
         * @param arrB 需解密的字节数组
         * @return 解密后的字节数组
         * @throws Exception
         */
        public byte[] decrypt(byte[] arrB) throws Exception {
            return decryptCipher.doFinal(arrB);
        }



        /**
         * 从指定字符串生成密钥，密钥所需的字节数组长度为8位
         * 不足8位时后面补0，超出8位只取前8位
         * @param arrBTmp 构成该字符串的字节数组
         * @return 生成的密钥
         * @throws java.lang.Exception
         */
        private Key getKey(byte[] arrBTmp) throws Exception {
            byte[] arrB = new byte[8];
            for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
                arrB[i] = arrBTmp[i];
            }
            Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");
            return key;
        }



        /**
         * 将byte数组转换为表示16进制值的字符串，
         * 如：byte[]{8,18}转换为：0813，
         * 和public static byte[] hexStr2ByteArr(String strIn)
         * 互为可逆的转换过程
         * @param arrB 需要转换的byte数组
         * @return 转换后的字符串
         * @throws Exception 本方法不处理任何异常，所有异常全部抛出
         */
        public static String byteArr2HexStr(byte[] arrB) throws Exception {
            int iLen = arrB.length;
            StringBuffer sb = new StringBuffer(iLen * 2);
            for (int i = 0; i < iLen; i++) {
                int intTmp = arrB[i];
                while (intTmp < 0) {
                    intTmp = intTmp + 256;
                }
                if (intTmp < 16) {
                    sb.append("0");
                }
                sb.append(Integer.toString(intTmp, 16));
            }
            return sb.toString();
        }



        /**
         * 将表示16进制值的字符串转换为byte数组，
         * 和public static String byteArr2HexStr(byte[] arrB)
         * 互为可逆的转换过程
         * @param strIn 需要转换的字符串
         * @return 转换后的byte数组
         * @throws Exception 本方法不处理任何异常，所有异常全部抛出
         */
        public static byte[] hexStr2ByteArr(String strIn) throws Exception {
            byte[] arrB = strIn.getBytes();
            int iLen = arrB.length;
            byte[] arrOut = new byte[iLen / 2];
            for (int i = 0; i < iLen; i = i + 2) {
                String strTmp = new String(arrB, i, 2);
                arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);
            }
            return arrOut;
        }
    }

